화학공학소재연구정보센터
Applied Surface Science, Vol.255, No.4, 1476-1478, 2008
Calculation of radiogenic Mg-26 of CAI minerals under high precision isotope measurement by SIMS
High precision Mg isotope measurements have been performed to determine radiogenic Mg-26 of CAI minerals by secondary ion mass spectrometry using Faraday cup multi-collection system. Terrestrial samples of spinel and augite, and synthetic glasses of melilite and fassaite, were prepared to correct instrumental mass fractionation. Reproducibility of Mg isotope measurements for each standard were limited to similar to 0.4 parts per thousand (2 sigma). On the other hand, the standard errors for one spot are similar to 0.05 parts per thousand (2 sigma). The poor reproducibility resulted from variations of instrumental mass fractionation among individual measurement spots. We propose novel calculation method of radiogenic Mg-26 considering instrumental and natural mass fractionation for each mineral. The overall measurement error of radiogenic Mg-26 of the minerals can be calculated less than 0.2 parts per thousand (2 sigma). This provides that the time resolution of early solar system chronometer was improved up to 100K year for similar to 20 mu m scale objects formed in the early solar system. (C) 2008 Elsevier B. V. All rights reserved.